The present invention relates to an electronic polynomial interpolation device for numeric controls of machine tools, particularly milling machines for the machining of dies, and to a machine which comprises said device.
In the machining of metallic dies made of steel, cast iron or aluminum and intended for the production of articles made of sheet metal or plastic or composite materials, the completely automatic finishing of said die by means of machine tools has now become fundamentally important.
Manual restarting of the finishing operations is in fact a task which requires great specialization and very long times, with consequent unacceptable production costs.
In the design of dies, the appearance of computerized systems commonly known by the acronym CAD (Computer Aided Design) has allowed to mathematically define the surface of said die, regardless of its complexity, and to consequently generate parameters. When these parameters are processed by other computerized systems commonly known by the acronym CAM (Computer Aided Manufacturing), suitable for generating trajectories, they allow, by means of the numeric control system, to move the tool of the machines so as to reproduce the mathematically expressed surfaces.
The greatest disadvantage of these known automation systems currently consists of the interaction between the CAM systems and numeric controls due to the intrinsic limitations of the latter.
Currently known numeric controls in fact require the trajectory of the path of the tool, which is generated by a CAM system starting from the mathematical definition of the surface of the part to be machined, to be a broken line, generally with a large number of segments in order to contain chordal error. This, first of all, significantly limits the advancement speeds of the tool, which decrease as the allowed chordal error decreases and in any case become critical for values in the range of 10,000 mm/min due to the large amount of data to be processed.
The intrinsic nature of broken-line trajectories in any case leads, even if chordal error is kept within very narrow limits, to the generation of "faceted" surfaces which require the subsequent and undesirable manual finishing of the die.